Thread tensioning attachment for sewing machines



Feb. 6, 1940. H. H. HOWELL 2,189,732

THREAD TENSIONING ATTACHMENT FOR SEWING MACHINES Filed June 2o, 193e 55 3mm/wom Patented Feb. 6, 1940 UNIT-ED STATES .PATENT OFFICE SEWING MACHINES Harpster H. Howell, Brighton, Mich.

Application June 20,

1 Claim.

This invention relates to a sewing machine and more particularly to a thread tensioning attachment for a sewing machine adapted for sewing leather goods or the like.

An object of this invention is to provide a thread tensioning attachment for a conventional sewing machine used in the stitching of leather goods such as shoes or other leather articles, the attachment being adapted to provide when occasion demands extra tension on the thread so as to provide extra tight stitches as where buckles, buttons or similar leather or other heavymaterial and also to provide an extra tensioning means for tightly holding the thread where cross stitching is being formed on leather or other heavy material.

In sewing machines at present available the thread passes through a pair of tensioning means which is adapted to tension the thread for noro mal stitching but Where extra heavy work is being performed or where it is desired to provide extra tension on the thread it is at present'necessary to, on each occasion, adjust the present tensioning device to meet the varying conditions.

' 5 'I'his results in considerable adjustment of the usual thread tensioning device and while the normal threadtensioning device may be capable of applying any desired tension on the thread, yet it is a difficult matter to return the tensioning :m device to what may be termed normal tension for normal usage.

It is therefore an object of this invention to provide an attachment for a Asewing machine which is so constructed that the thread after :n passing through the present tensioning device on the machine may be passed through or about the lsupplemental tensioning device so that any desired additional tension may be appliedvto the thread without in any way affecting the tension 1.1) placed on the thread by the normal tensioning means. With the use of this supplemental tensioning device after the work has been performed which requires extra tension on the thread, the thread can be disengaged from the supplemental 45 tensioning device without requiring a. rethreading of the thread through the guide and tensioning devices as the thread is placed under the extra tension at an intermediate point between the needle and the tensioning device at present .in on the machine.

A further object of this invention is to provide an attachment of this kind which can be applied to the machine without requiring the drilling and threading of any additional holes in the head of 55 the machine so that the device can be quickly articles are stitched onto y 193s, serial No. 214,789

(c1. 11a-59) j applied and if desired can be quickly taken on although when the device is not in use the device can be left on the machine where it will not interfere with the normal operation of the machine as existed before the addition of the sup'- plemental tensioning device.

A still further object of this invention is to provide a tensioning means of this character which is exceedingly simple in construction and which will not get out of order, the device being so constructed that it may be manufactured at a relatively small cost and may be applied to the machine by the useV of a screw driverr which is used for removing a headed screw at present on the machine and securing the support for the attachment on this headed screw.

To the foregoing objects and to others which may hereinafter appear, the invention consists of the novel construction, combination and arrangement of parts as will be more specifically referred to and illustrated in the accompanying drawing wherein is shown an embodiment of the invention, but it is to be understood that changes, variations and modications may be resorted to which fall within the scope of the invention` as claimed.

In the drawing:

Figure 1 is a fragmentary top plan of the head of a sewing machine adapted for use in sewing leather goods such as shoes or the like having an attachment mounted thereon constructed according to an embodiment of this invention,

Figure 2 is a fragmentary side elevation of the device shown in Figure 1, and

Figure 3 is an enlarged fragmentary sectional View taken onthe line 3-3 of Figure 1.

Referring to the drawing, the character H designates generally the head of a sewing machine of conventional construction which is supported by a supporting arm or member I0. A needle operating lever or rock arm Il is disposed above the supporting arm I0 and is connected to an operating means (not shown) whereby the lever II may be vertically rocked so as to reciprocate a needle carrier I2 which is connected to the arm II by a connecting member I3.

' A pair of thread tensioning plates I4 are mounted on a vertically disposed stud I5 and are tensioned by means of a tensioning nut I6 which engages a tensioning spring I1 disposed about the stud I5. The thread T is adapted to pass between two tensioning plates I4 and in the present instance the thread T after passing the tensioning members I4 extends through a guide eye I8 secured to -thf head H by means of a headed screw I9. 'I'he thread T then extends upwardly through an eye 20 provided in the outer end of atake-up lever 2| mounted on a pin 22 carried by the arm lever II. The rear end of this lever 2| is provided with an obliquely disposed extension or lug 23 which engages a flat spring 24 secured to the top of the lever I I by means of a bolt or screw 25. The hereinbefore described construction is the present and normal construction of a sewing machine wherein the thread T is tensioned by adjustment of the tensioning nut I6. As shown in Figures 1 and 2 the thread T initially engages over a guide pin 28 which is ilxed to the top of the head H adjacent the plates I4.

In order to provide a means whereby additional tension of a predetermined character or degree may be provided on the thread T after passing the tensioning members I4, I have provided a thread tensioning attachment which comprises a base or supporting plate 21 which is provided with a suitable aperture for receiving the screw I9 so that the plate 21 may be bolted to the top of the head H. The guide eye I8 is adapted to engage on the upper side of the plate 21 as shown in Figure 1.

A vertically disposed stud 28 rises vertically from the plate 21 and in the present instance this stud 28 is provided with threads 29 at the lower end thereof and a pair of nuts 30 and 3| are threaded onto the stud 28 engaging against the lower and upper sides respectively of the plate 21 so as to tightly hold the stud 28 on the plate 21. An inverted cup-shaped member or washer plate 32 engages about the stud 28 and is provided at its bottom with an annular flange 33 seating upon the upper surface of the plate 21. The washer or cup-shaped member 32 is adapted to enclose the holding nut 3| and at the same time provide a means 'for supporting a set of superimposed axially apertured thread tensioning plates of disc-like form above and spaced from the nut 3|. The set consists of four plates. The two lower superimposed plates of the set are indicated at 34 and the two upper superimposed plates of the set at 35. The outer edge surfaces of the plates 34 are oppositely beveled, as at 36 to provide a V-shaped thread receiving edge for facilitating the thread entering between the plates 34. The outer edge surfaces of the plates are oppositely beveled, as at 31 to provide a V-shaped thread receiving edge for facilitating the thread entering between the plates 35. When using the attachment preferably, the thread will be arranged selectively between the plates 34 or between the plates 35, and not positioned between the upper plate of the plates 34 and the lower plate of the plates 35. The setting up of the plates of the set in the manner as stated will provide for selectively elevating the outer portion of the stretch of the thread leading from the stud I5 to the stud 28 for the purpose of decreasing slack in said stretch.

A tensioning spring 38 forms an element of the attachment and which is common to the plates of the set. The lower end of spring 38 permanently bears against the upper one of the plates 35. The upper end of the spring 38 engages against a nut 39 which is threaded onto threads 40 carried by the upper end of the stud 28. By means of the nut 39 the desired tension may be applied to the thread tensioning plates 34 and 35.

The thread T after passing the tensioning members I4 engages through the eye Il and is then passed between a selected pair of plates 34 or 35. From this point the thread T is extended through a guide eye 4| which is fixed to the plate 21 and then the thread is extended upwardly through the eye 20 and down through a thread passage or channel 42 provided in the carrier I2. The guide eye 4I is formed by bending a small piece of wire in a loop with the eye or the looped portion 43 thereof substantially horizontal and having a stem 44 extending vertically downwardly and secured by any suitable means as by riveting, welding or the like to the plate 21.

In the use of this tensioning attachment during the normal operation of the sewing machine the thread T may pass between the tensioning members I4, the eye I8 and then be extended upwardly through the eye 20. The pull or tension applied to the thread T will draw the lever 2| downwardly against the tensioning of the spring 24 so that that portion of the thread T extending downwardly from the eye 20 through the channel 42 to the needle will be placed under constant tension. However, when it is desired to place additional tension on the thread T without in any way aiecting the adjustment or tension oi' the tensioning members I4 the thread T may be looped about the stud 28 between a selected pair of plates 34 or 35. This may be done by taking the thread as it passes through the eye I8 as shown in Figure l and then looping it about the stud 28 and between a selected pair of tensioning plates. The thread is then engaged with the eye 4I and from there rises at an oblique angle to the eye 2U. With this additional tensioning means the lever 2| will be pulled downwardly to a greater degree thus flexing the spring 24 additionally and placing the thread T under a considerable additional tension. This additional tension may be applied to the thread where patches are being sewed onto shoes or where cross stitching is being used to repair split portions of leather or where buckles, buttons or the like are being stitched with the machine onto leather or other heavy material. When the use for the extra tension is not present the thread T may be disengaged from the eye 4I and from the tensioning plates 34 or 35, this procedure being performed without breaking the thread or without pulling the thread out of the needle as it is only necessary to pull the thread laterally to the left as viewed in Figure l from between the tensioning plates and then disengaging the thread from the additional guide eye 4I. During all this time the thread T will remain engaged with the remaining guide eye I8.

The tensioning structure of the attachment is not disposed in alignment with the thread tensioning means of the sewingl machine and such structure is arranged on the outer portion of the supporting plate. The inner portion of the latter is secured to the head of the machine. The thread guides are disposed in spaced non-aligned relation. The thread guides are spaced rearwardly from and disposed in angular relation with respect to the axis of the tensioning structure of the attachment. One of the guides is for the purpose of guiding the thread from the thread tensioning means of the sewing machine to the thread tensioning structure of the attach ment. The other of the guides is for guiding the thread from the thread tensioning structure of the device to the eye of the take-up lever.

It will therefore be apparent that an exceedingly simple thread tensioning means has been provided in the form of an attachment which may easily and quickly be applied to the head of a sewing machine so that any desired extra tension may be exerted on the thread without disturbing the normal tensioning devices or device at present in use.

This device may be attached to the head of the sewing machine without requiring the drilling of any extra holes and the threading of such holes as at present the guide eye I8 is secured to the head H by means of the headed screw I9. If necessary this headed screw I9 may be replaced by a slightly longer screw but with this exception, no changes whatever are necessary in the construction of the machine in order to apply the attachment. It w'lll therefore be apparent that the operator of the machine may apply this attachment with the use of a screw driver and this attachment when applied will not interfere with the normal use of the original tensioning device as hereinbefore stated.

what I claim is:

A detachable supplemental tensioning device operatively associated with a standard tensioning device and take-up arm of a sewing machine; the supplemental tensioning device comprising a supporting plate having a portion thereof detachably secured to the sewing machine head forwardly of the standard tensioning device and the remaining portion of the plate overhanging the forward face of the head, a thread tensioning structure secured to the overhanging portion of the plate, a pair of spaced thread guides carried by and extending upwardly from said plate, said guides being disposed on opposite sides of a vertical plane extending centrally through said tensioning structure and said take-up arm, the sewing machine thread normally engaging the standard tension and the take-up arm and the guides serving to direct the thread from the standard tensioning device to the supplemental tensioning device and therefrom to the take-up arm.

HARPSTER H. HOWELL. 

